An electronic apparatus is often equipped with a phase-locked loop. For example, a communication system often communicates on the basis of a clock signal generated by the phase-locked loop. Specifically, for example, a transmission unit transmits a data signal, using a clock signal generated by the phase-locked loop. Further, for example, a receiving unit receives a data signal, using a clock signal generated by the phase-locked loop. NPL 1 discloses a phase-locked loop usable in such a communication system.